It is well known that, by intake of marijuana, various psychiatric or neurological reactions such as confusion of temporal or space sense, euphoria, alteration of memories, analgesia, hallucination and the like would be produced. The compounds generally referred to as “cannabinoid” including Δ9-tetrahydrocannabinol (Δ9-THC) are responsible for many of such reactions. The effect of cannabinoid is considered to be produced by an interaction between the compound and its endogenous specific/high-affinity receptors. Two subtypes of cannabinoid receptors (CB1 and CB2) have been identified and cloned. The CB1 receptor is distributed in central nervous system (CNS) regions including brain (Non-patent literature 1) while the CB2 receptor is distributed in immune system including spleen (Non-patent literature 2).
Substances having affinity to such cannabinoid receptors (agonists, antagonists or inverse agonists) may produce various pharmacological effects like marijuana. In particular, substances having affinity to central CB1 receptor may be useful for treatment of a CNS disease such as a psychotic disorder, a neurological disorder and the like.
There have been known various compounds, including pyrazol-3-carboxamide compounds such as SR141716 (Non-patent literature 3), 4,5-dihydropyrazole compounds such as SLV-319 (Non-patent literature 4), dihydropyrazolo[3,4-c]pyridin-7-one compounds, 2H-pyrazolo[4,3-d]pyrimidin-7(6H)-one (Patent literature 1) and the like as the substances having affinity to such cannabinoid receptors. Among them, at least SR141716 and SLV-319 are under clinical studies on the efficacy thereof as anorexigenics (anti-obesity agent).    (Patent literature 1) WO2004/094417    (Non-patent literature 1) Nature, Vol. 346, 1990, pp 561-564    (Non-patent literature 2) Nature, Vol. 365, 1993, pp 61-65    (Non-patent literature 3) Life Science, Vol. 63, 1998, PL113-PL117    (Non-patent literature 4) Journal of Medicinal Chemistry, Vol. 47(3), 2004, pp. 627-643